Metal-finishing apparatus

ABSTRACT

A metal-finishing assembly which has a quickly replaceable abrasive and lookthrough viewing means for continually observing the surface being finished. One form of the assembly includes a disk-shaped member having radially extending abrasive tubes resiliently mounted on arms. The assembly is attached to a shaft by locking means which may easily e disengaged to allow the tubes to be rotated on the arms.

United States Patent lnventor Antonio Pirrello Lincoln Park, Mich.

Appl. No 877,247

Filed Nov. 17, 1969 Patented Aug. 3, 1971 Assignee General MotorsCorporation Detroit, Mich.

METAL-FINISHING APPARATUS 6 Claims, 3 Drawing Figs.

US. Cl 51/358, 51/1701, 51/109 Int. Cl ..B24d 17/00, B24b 23/00, 13241:9/00 Field of Search 51/358,

i 1 a i g [56] References Cited UNITED STATES PATENTS 3,452,485 7/1969Broscoff 51/109 2,420,876 5/1947 Freud 51/90 1,654,275 12/1927 Strand...15/230 1,498,224 6/1924 Atwood..... 125/5 241,351 5/1881 Graham 125/5Primary ExaminerHarold D. Whitehead Attorneys-William S. Pettigrew andRobert J. Wallace ABSTRACT: A metal-finishing assembly which has aquickly replaceable abrasive and lookthrough viewing means forcontinually observing the surface being finished. One form of theassembly includes a disk-shaped member having radially extendingabrasive tubes resiliently mounted on arms. The assembly is attached toa shaft by locking means which may easily e disengaged to allow thetubes to be rotated on the arms.

PATENTED AUG 3 Ian INVEN'I'UR ATTOFH-lh( METAL-FINISHING APPARATUS Thisinvention relates to metal finishing, and particularly to ametal-finishing assembly adaptable for use in a portable metal-finishingtool.

During the substantially continuous metal-finishing operations such asone encounters a commercial assembly line, the abrasive of ametal-finishing surface wears off, and must be frequently replaced.Often the abrasive is in disk form adhesively attached to a backup plateor pad. Periodic replacement of this type of abrasive is often undulytime consuming and can, therefore be costly. This can be particularlytrue, when the metal finishing is being performed on a high volumecommercial production line where only a limited time is available formetal finishing or working each successive unit.

If the abrasive is not replaced frequently, a smooth area can appearthereon. A severely worn or smooth area on an abrasive can cause highand low spots to appear in the surface of the work. If one ultimatelydesires a generally specular appearance in the work surface, after afinal painting, such a surface must often be refinished. Refinishingsuch a surface adds a considerable extra cost to the overall cost of themetalfinishing operation. It is generally less costly to simply changeor replace abrasive disks more frequently than to incur refinishingcosts. Often when the abrasive is replaced, only a minor portion of theabrasive area is won. However, the entire disk is usually discarded.This, of course, is inefficient use of such a abrasive disk.

Furthermore, the usual prior art type of hand-held tool must beperiodically removed from the surface being finished in order to inspectthat surface. Repeated removal of a tool from the metal surface forinspection purposes can be time consuming. Besides, placing the toolback onto the surface, if not done properly can cause edge cutting andditching on the surface.

Accordingly, it is a principal object of this invention to provide ametal-finishing assembly wherein a worn abrasive sur face can easily andquickly be replaced.

Another object of this invention is to provide a metal-finishingassembly wherein the entire abrasive surface can be used moreefficiently.

Still another object of this invention is to provide a metalfinishingassembly wherein the surface being finished can be continually observedduring the metal-finishing operation.

Other objects, features and advantages of this invention will becomemore apparent from the following description of the preferred exampleand from the drawings in which:

FIG. 1 is a plan view of a metal tool having a finishing assembly madein accordance with this invention;

FIG. 2 is a partial sectional view taken along the line 22 of FIG. 1;and

FIG. 3 is a view showing the parts of the assembly separated from eachother.

Referring now primarily to FIG. I, it shows a portable machine includinga disk-shaped metal-finishing assembly and a tool 10. Tool has inletmeans 12 and a conventional airdriven motor having a shaft 14. Tool 10is adaptable to be hand held generally at handles 16 and 18. Thedisk-shaped metal-finishing assembly includes a central hub havingradially extending abrasive tubes with wedge-shaped openings 19therebetween. The openings provide lookthrough viewing means when theassembly is rotated. The disk assembly is rigidly attached to shaft 14,and made rotatable therewith, by locking means in the form of a nut 20recessed within the hub of the assembly.

The assembly includes, as is best shown in FIG. 3, an inner backup plate22 and an outer abrasive holding member 25 adaptable to be recessedwithin plate 22. Both plate 22 and member 24 are made of aluminum.However, any durable plastic or metallic material is suitable.

Member 24 includes the outer hub segment 26 of the assembly and has acentral aperture 28 for receiving shaft 14. Aperture 28 is locatedwithin a recess 30 which accommodates nut 20. A pair of registrationopenings afelocated on opposite sides of recess 30 on hub segmentplurality of abrasive receiving arms 34 integrally formed about theperiphery of hub segment 26 extend radially therefrom about 1.5 inches.Corresponding parts of each are angularly displaced from each otherabout 30. Hub segment 26 has. a diameter of about 3 inches. Arms 34 areof semicircularlike cross section, and have a radius of curvature ofabout 0.375 inch and a length of about 1.5 inches. Each arm 34 includesan outer flat surface having a width of about 0.70 inch. The flexibleabrasive tubes each have a length of about 1.5 inches and a diameter ofabout 0.75 inch. Hence, they are loosely mounted on each arm 34. Eacharm is beveled at its respective free ends to facilitate positioning thetubes thereon.

Backup plate 22 includes the inner hub segment 36 of the assembly and aperipheral rim 38 and] a plurality of web elements 40 therebetween. Plat22 further includes a central aperture 42, for receiving shaft 14, and apair of upstanding index plugs 44. The web elements 40 are thinner thanrim 38, forming a recess 46 within plate 22 for receiving member 24.Corresponding parts of each web element 40 are similarly angularlydisplaced from each other about 30. Each web element has a width ofabout 0.5 inch and a thickness of about 0.25 inch.

Index plugs are insertable within openings 32 of member 28 to generallyalign each arm with a corresponding web element and to loosely seatmember 24 within recess 46. Each web element 40 thus registers with anarm to form a backing for an abrasive tube. Each arm 34 terminatesclosely adjacent the inner periphery of rim 38. The locking nut 22securely seats member 24 within recess 46. Thusly seated, the webelements of member 24 and the arms 34 cooperate to clamp the tubularabrasives. This forces the abrasives to generally remain contiguous tothe rounded surface of the arms. The abrasive generally overlying theflat surface of each arm 34 is generally free to resiliently follow thesurface contours of the work.

As can easily be understood, the wedge-shaped openings adjacent eachabrasive tube provide lookthrough viewing means allowing one tocontinually observe the work as the assembly is rotated by shaft 14.Moreover, it should easily be understood that whenever the abrasiveengaging the work becomes worn, one merely has to rotate the tubes onthe arms after disengaging the recessed locking means. Accordingly, theentire abrasive area of a tube may be utilized.

It should be further understood that while certain dimensions and angleshave been used in describing this preferred embodiment, the invention isnot to be so limited. For example, the corresponding parts of theabrasive receiving arms as herein described have an angular displacementof 30; other angular displacement can, of course, be suitable. Likewise,one may use an appropriate grit size that is suitable for a particularapplication. However, it has been found that for finishing sheet metalat a speed of about 3,000 rpm, a grit size of about 30 to is preferable.

What I claim is as follows:

1. A metal-finishing apparatus which comprises a hub having a centralaperture for receiving ashaft, a rim coaxial with said hub, a pluralityof arms each having a free end extending radially from said hub,abrasive tubes mounted on each of said plurality of arms, backing meansfor each of said abrasive tubes, and said arms, aid backing means andsaid abrasive tubes cooperating to define a plurality of openingsbetween said hub and said rim providing lookthrough viewing means as thedisk is rotated.

2. The metal-finishing apparatus recited in claim I wherein theplurality of arms each terminate closely adjacent the rim, the backingmeans are a plurality of web elements each of which is closely adjacentone of the plurality of arms and generally coextensive therewith, andthe abrasive tubes are resiliently mounted on each of the plurality ofarms.

3. A metal -finishing apparatus which comprises a hub having an outersegment, an inner segment, and a central aperture for receiving a shaft,a rim coaxial with said hub, a plurality of arms integralwith said outersegment and of semicircularlike crosssection each having a free end andextending radially therefrom terminating closelyv adjacent said rim,abrasive tubes loosely mounted on said arms, a plurality of web elementsintegral with said inner segment and said rim, each of 5 said webelements generally coextensive with a corresponding arm providing abacking for each of said tubes and said arms, locking means securing thedisk to the shaft and urging said web elements into clamping engagementwith said tubes restraining movement on said arms, said web elements andsaid tubes cooperating to define a plurality of openings between saidhub ands'aid rim providing a lookthrough viewing means as the disk isrotated by the shaft.

4. A metal-finishing assembly which comprises a backup plate includingan inner hub segment having a central aperture, a coaxial rim and aplurality of web elements extending radially from said hub intersectingsaid rim forming a recess about the periphery of said rim, an abrasiveholding member seated within said recess, said member having and outerhub with a central recess having an aperture and a plurality of armsextending radially from said outer hub terminating closely adjacent saidrim, an abrasive tube mounted on each of said plurality of arms, andsaid arms, said web elements and said tubes cooperating to define aplurality of openings between said hubs and said rim providinglookthrough viewing means as the disk is rotated.

5. The metal-finishing assembly recited in claim 3 wherein the outer hubof the abrasive holding member has at least one index opening and thebackup plate has at least one upstanding index plug within the indexopening.

6. A metal-finishing assembly in the form of a diskadaptable to berotated by a shaft which comprises a backup plate including an inner hubsegment having a central aperture, a coaxial rim, a plurality of webelement extending radially from said inner hub segment intersecting saidrim forming a recess about the periphery of said rim and a pair ofupstanding index plugs on opposite sides of said hu b, an abrasiveholding member having an outer hub with a central recess including anaperture, and a plurality of arms'of semicircularlikc cross sectionhaving an outer flat surface and an inner rounded surface extendingradially from said outer hub, and a pair of index openings on oppositesides of said central recess receiving said index plugs seating saidmember within said recess about the periphery of said rim generallyaligning each of said plurality of arms coextensively overlying one ofsaid plurality of web elements and closely adjacent said rim, anabrasive tube resiliently mounted on each of said arms, said webelements, said arms and said tubes defining a plurality of openingsbetween said hubs and said rim providing lookthrough viewing means asthe disk is rotated, and locking means in said central recess of saidsecond hub securing the assembly to the shaft and urging said webelements into clamping engagement with said tubes restraining movementof said tubes on said arms.

1. A metal-finishing apparatus which comprises a hub having a centralaperture for receiving a shaft, a rim coaxial with said hub, a pluralityof arms each having a free end extending radially from said hub,abrasive tubes mounted on each of said plurality of arms, backing meansfor each of said abrasive tubes, and said arms, aid backing means andsaid abrasive tubes cooperating to define a plurality of openingsbetween said hub and said rim providing lookthrough viewing means as thedisk is rotated.
 2. The metal-finishing apparatus recited in claim 1wherein the plurality of arms each terminate closely adjacent the rim,the backing means are a plurality of web elements each of which isclosely adjacent one of the plurality of arms and generally coextensivetherewith, and the abrasive tubes are resiliently mounted on each of theplurality of arms.
 3. A metal -finishing apparatus which comprises a hubhaving an outer segment, an inner segment, and a central aperture forreceiving a shaft, a rim coaxial with said hub, a plurality of armsintegral with said outer segment and of semicircularlike cross sectioneach having a free end and extending radially therefrom terminatingclosely adjacent said rim, abrasive tubes loosely mounted on said arms,a plurality of web elements integral with said inner segment and saidrim, each of said web elements generally coextensive with acorresponding arm providing a backing for each of said tubes and saidarms, locking means securing the disk to the shaft and urging said webelements into clamping engagement with said tubes restraining movementon said arms, said web elements and said tubes cooperating to define aplurality of openings between said hub and said rim providing alookthrough viewing means as the disk is rotated by the shaft.
 4. Ametal-finishing assembly which comprises a backup plate including aninner hub segment having a central aperture, a coaxial rim and aplurality of web elements extending radially from said hub intersectingsaid rim forming a recess about the periphery of said rim, an abrasiveholding member seated within said recess, said member having and outerhub with a central recess having an aperture and a plurality of armsextending radially from said outer hub terminating closely adjacent saidrim, an abrasive tube mounted on each of said plurality of arms, andsaid arms, said web elements and said tubes cooperating to define aplurality of openings between said hubs and said rim providinglookthrough viewing means as the disk is rotated.
 5. The metal-finishingassembly recited in claim 3 wherein the outer hub of the abrasiveholding member has at least one index opening and the backup plate hasat least one upstanding index plug within the index opening.
 6. Ametal-finishing assembly in the form of a disk adaptable to be rotatedby a shaft which comprises a backup plate including an inner hub segmenthaving a central aperture, a coaxial rim, a plurality of web elementextending radially from said inner hub segment intersecting said rimforming a recess about the periphery of said rim and a pair ofupstanding index plugs on opposite sides of said hub, an abrasiveholding member having an outer hub with a central recess including anaperture, and a plurality of arms of semicircularlike cross sectionhaving an outer flat surface and an inner rounded surface extendingradially from said outer hub, and a pair of index openings on oppositesides of said central recess receiving said index plugs seating saidmember within said recess about the periphery of said rim generallyaligning each of said plurality of arms coextensively overlying one ofsaid plurality of web elements and closely adjacent said rim, anabrasive tuBe resiliently mounted on each of said arms, said webelements, said arms and said tubes defining a plurality of openingsbetween said hubs and said rim providing lookthrough viewing means asthe disk is rotated, and locking means in said central recess of saidsecond hub securing the assembly to the shaft and urging said webelements into clamping engagement with said tubes restraining movementof said tubes on said arms.